This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Objective: To better understand the digestive physiology of non-human primates by measuring the extent of passive absorption of water-soluble nutrients. This project has important implications for understanding the digestive physiology of humans and non-human primates, and also for understanding vertebrate nutritional ecology and toxicology. Many nutrients, natural toxins and synthetic toxins and drugs are hydrosoluble. Efficient transport of hydrosoluble chemicals across the vertebrate small intestine likely depends on membrane transport proteins (mediated transport);however, some animals can efficiently transport these chemicals through the gaps between cells (i.e., by a passive, paracellular pathway). We used physiological and pharmacokinetic techniques to test the extent of passive absorption in primates. This study began during the fall of 2003 and was completed by December of 2005. This research used WNPRC Animal Services. Funding ended before this reporting period. One publication is pending in 2009.